For the optical determination of fluid chemistry or liquid samples respectively photometric analysis is commonly used and known in the art. E.g. proposed is a disk-like rotatable device on which a plurality of receptacles like cuvettes are arranged for the collection of fluid samples, the receptacles each are arranged within a photometric detection path, the respective light beam being absorbed partially for the analysis of the sample or its chemistry respectively. Photometric determination of fluid chemistry is in particular used for blood analysis, urine analysis or for any other liquid samples, where various fluid samples such as e.g. blood samples are being placed within sample cuvettes and light beams are being passed through the cuvettes, the light being partially absorbed for analysis of the blood samples.
In U.S. Pat. No. 5,122,284 a device for optically analysing biological fluids is described. On a disk a plurality of peripheral cuvettes is arranged, each of which is connected to a central connection chamber via a bifunctional path for the inlet flow of liquid into the cuvette and flow of gas out of the cuvette. A light beam oriented generally parallel to the axis of rotation is deflected once so that is passes horizontally through the fluid in the cuvette and then detected for analytical purposes. Alternatively a horizontal beam maybe once deflected vertically after passing through the fluid.
In U.S. Pat. No. 5,478,750 again photometric analysis of blood samples arranged on a rotatable disk is described, measuring the concentrations of substances like blood cell components within the liquid blood sample. The various fluid samples are arranged in cuvettes on the disk and for analytical purpose a light beam guided in perpendicular direction onto the disk surface is deflected in direction to the cuvettes within the plane of the disk.
In most known analytical devices the arrangements of the optical means and of the liquid sample containing cuvettes are arranged such that the direction of the light beam is usually in line with the radius of the rotatable disk, which means the optical deflection means or the reflective mirrors are arranged perpendicular to the radius of the rotatable disk.
Furthermore in some known devices such as described e.g. in U.S. Pat. No. 5,122,284 gas inclusions within the liquid may influence or disturb the optical analyses as liquid flow and gas removal is mixed up.
To minimize any absorption or negative influence of the material of the rotatable disk it is usually made out of a thermoplastic transparent polymer, such as e.g. poly(methyl methacrylate) (PMMA), polycarbonate, polystyrene, transparent copolyamide, etc. where so far PMMA has preferably been used. The disk-like analytical devices are usually manufactured using injection moulding technique. The optical means for the deflection of the light beam into the direction to the liquid sample containing cuvettes is achieved by providing a surface within the disk at an angle of 45° to the plane of the disk, so that the perpendicular arriving light beam is deflected without practically any absorption by the transparent polymer of the disk-like device. For producing such surfaces with a 45° angle usually respective inserts are arranged within the mould which means, that for each reflection surface a respective insert has to be arranged within the mould before the injection moulding procedure. The liquid polymer-melt is introduced into the mould at the center of the disk, which means at the rotation axis of the disk-like device, the flow of the liquid polymer is directed radially outward which may cause problems at the locations, where the inserts are arranged for the production of the reflective zone. The problem occurs due to the fact that the liquid polymer-melt is flowing around the insert, which is arranged perpendicular to the radial outward direction of the flow, so that the flow surrounds on both sides the insert for being mixed again at the backside of the insert. Practical experience showed that due to this mixing zone on the reflective surface at least partial polarisation of the light to be deflected in the direction to the cuvettes may occur, which of course is not desirable.
Furthermore the insertion of all the various inserts before the injection moulding procedure is time consuming and as a consequence the production procedure as used so far for the production of the known disk-like devices for analytical purpose is not optimal.
It is therefore one object of the present invention to optimize the production process for analytical devices as described above for photometric detection, where the surfaces of at least most of the reflective surfaces or mirror-like surfaces may guarantee optimal reflective properties, so that the deflection of the light beam is not affected by any defects within the surface.
It is a further object of the present invention to reduce the handling before and/or during the production of photometric analytical devices as described above in respect to simplify the placement of any inserts into the moulding tool establishing the mirror-like or reflective surfaces within the disk-like device for photometric analytical purpose.
It is again a further object of the present invention to reduce the influence of any gas or air inclusions within the liquid to be analytically detected which might occur due to inappropriate feeding of the receptacle with the liquid to be e.g. optically analysed.